core: frontend: router: Remove unused imports #1790

Job	Run time
frontend-tests	1m 43s
python-tests	2m 34s
deploy-docker-images (bootstrap, blueos, linux/arm/v7,linux/arm64/v8,linux/amd64)	1m 4s
deploy-docker-images (core, blueos, linux/arm/v7,linux/arm64/v8,linux/amd64)	16m 40s
deploy-raspberry-image	0s
	22m 1s

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